http://www.moparmusclemagazine.com/..._0312_solid_vs_hydraulic_lifters/viewall.html
This article shows a basic example of how much extra duration and overlap is needed to create the same quality engine switching from hydraulic cam to solid cam.
The hydraulic cam used in this example as a before spec is the 231/237 XE275HL, used in several 400hp 318 buildup articles. and it's generally agreed that it's an appropriate cam for a street/strip 318.
They replaced it with a 239/247 solid cam and got identical idle vacuum and cranking pressure.
I would consider running that exact grind if it wasn't custom. I don't think I could afford to wait the turn around time in a custom cam.
However this test was done with a 440.